very strange phenomenon

[xhyr]

int main(int argc, char** argv) { TGAImage image(image_width, image_height, TGAImage::RGB);

for (int i = 0; i < image_width; ++i)
	image.set(i, 10, red);
//image.flip_vertically(); // i want to have the origin at the left bottom corner of the image
image.write_tga_file("output.tga"); 
return 0;

}

//when image_width = image_height = 800，the line is out of bound. But when width and height less than 700, the line is visible

[xhyr]

the tgaimage.h and tgaimage.cpp are all the same as this repository.

[ssloy]

indeed very strange, can you give me the complete sources as well as the resulting tga files, please?